Cartridge fuse



Patented Dec. 8, 1953 UNITED STATES ATENT OFFICE 4 Claims.

This invention relates to electric circuit breakers, particularlythermal circuit breakers and more especially to fusible element thermalbreakers.

A principal object of this invention is to provide a knife bladecartridge fuse which is so constructed that all current carrying partsare associated in one assembly which may be inserted in and withdrawn asa whole from a cartridge provided with metallic end ferrules without theuse of end ferrule caps.

A further object of the invention is the construction of a cartridgefuse of the kind specified which includes an insulating stationary barfor separating knife blades which includes means for preventing unduewear upon the end surfaces of the spacer bar.

Other objects and advantages will appear as the description of theparticular physical en1bodiment selected to illustrate the inventionprogresses and the novel features will be particularly pointed out inthe appended claims.

In describing the invention in detail and the particular physicalembodiment selected to illustrate the invention, reference will be hadto the accompanying drawings and the several views thereon, in whichlike characters of reference designate like parts throughout the severalviews, and in which:

Figure 1 is a side elevational view of a knife blade cartridge fuseembodying my invention; Fig. 2 is a cross sectional view of the deviceas shown by Fig. l on a plane parallel to the broad faces of the knifeblades; Fig. 3 is a cross section of the device of Fig. 1 on a plane ata right angle to the plane upon which Fig. 2 is taken; Fig. 4 is a crosssection of the device of Fig. l in a plane parallel to the broad facesof the knife blades but viewed in a direction 180 from the direction inwhich Fig. 2 is viewed.

My improved knife blade fuse includes a cartridge I of insulatingmaterial, preferably horn fibre.

My invention utilizes two metallic end ferrules, one on each end of thecartridge I, as 3 and 5. These end ferrules may be made of any suitableor appropriate metal, preferably brass. They may be attached to thecartridge I in any suitable or preferred manner. I have illustrated themas secured by matching threads, as l, and with the additional securityof a threaded screw 9 passing through the ferrule and into the materialof the cartridge I. Of course, I do not mean to exclude by the use of ascrew 9, the use of a through rivet headed on both ends. I do not meanto exclude by the showing the use of an unthreaded cap.

The ferrule 5 is provided with an internal shoulder Ii. The ferrule 3 isprovided with an internal thread I3.

All of the other parts of my fuse are embraced Within What I call theknife blade assembly which includes two knife blades, one It at one endand the other ii at the other end.

The knife blade assembly includes a stationary bar l9 of insulatingmaterial. This may well be made of harm fibre.

At each end of the spacer bar it I provide a butt plate as 2! and .23.Each of these butt plates has a fiat plate-like portion as 25 and rightangle extensions at each end, as 21 and 23. The right angle extension 2iseats on the end of the spacer bar. The right angle extension 29 seatson the end of a knife blade. Each of the butt plates is firmly attachedto the stationary bar It by through rivets, as 3| and 33.

Each of the knife blades embraces two rectangular portions. Knife bladeI5 has the rectangular portions 35 and the tang end portion 3'1. As oneend of the knife blade is a tang end portion, the butt plates, as 2 I,are interposed between the tang ends of the knife blades and the spacerbar E9, and the right angle portion, as 29, bears against the end of atang end.

The spacer bar, the butt plates and the tang ends are each formed withthrough bores, as 331 and 4 I. Within the through bores, there arepositioned threaded bolts 53 and 45. The threaded bolts are eachprovided with a washer, as a? and a nut, as it. By means of the bolts t3and #15 and the nuts and washers as 4'! and 39, the fusible link 5| ispositioned spanning the tang ends of the knife blades and is heldsecurely in position by the nuts and washers so that a firm unitaryselfassembly is made of the spacer bar IS, the butt plates 2| and 23,the knife blades i5 and fl, fusible link 5| and the bolts and ittogether with their washers, as ll and nuts, as it.

On knife blade i5 between the shoulders 53 and 55 and the right angleportion 2? of the butt plate 2| is positioned a metallic cup 571. Thismetallic cup 5? is formed with a shoulder 59 to cooperate with theshoulder I I of the ferrule 5 and with a peripheral surface 6! of anexternal diameter proper to centralize the metallic cup El in thethrough orifice 63 of the end ferrule 5. The metallic cup I I is alsoprovided with a peripheral surface 55 which just fits the internal bore6'! of the end ferrule i. This peripheral surface is covered withcries-cross ridges and depressions, that is, it is knurled. The objectof this knurling is to provide a surface which will tend to catch andhold vaporized fusible strip metal.

- end ferrule 3.

- two vents, 9| and 93.

The metallic cup 51 is also provided with through vent bores, as 69 andII. In addition, a metallic washer I3 is provided with a slot 15embracing the tang 31 and positioned over the vents 69 and II andbetween the metallic cup 51 and the butt plates, as 2|.

As will be hereinafter more fully described, there are means associatedwith the other end of the cartridge fuse by which the metallic cup 51isforced firmly against the shoulder ll of the ferrule 5 and the spacerbar IS) with the butt plate 2| is forced firmly against washer Hi -andwasher I3 is forced firmly against therinside of the cup 51.

At the other end of the fuse from knife b1ade- 'ber 81 of the butt plate23. The metalliccup l9 is provided on a portion of-- its periphery withthreads 89 cooperating with'threads IS on the The cup 19 is alsoprovided with The metallic washer 95 is provided with the slot 91embracing the tang I1 and is. interposed between the metallic cup 19 andthe right angle portion 81 of-thebuttplate 23.

Cup 19 by means of thread BBmay be screwed firmly into the end of theferrule by cooperation with the thread I3 on the ferrule 3. When this isdone, the washer 95-bears firmly against the butt plate 23 and the cup19 bearingagainst the washer 95 forcing all the parts toward the right,i as viewed in Fig. 3, so that cup 51 bears tightly against the shoulderH on the other end of the cartridge. In order to facilitate thecooperation of threads 39 and B, the end wall- 99 of the .metallic cup19 is extended outwardly to have an external diameter greaterathanthediameter of the adjacent ferrule 3 and the 'peripheralsurface isknurledas: shown most clearly in Fig. l at. H) I This lmurling not onlyprovides a; convenient and eflicient' means 'forassemblingthe parts, butit also serves as anindicator sothat one about to take-thefuseapartknows that' the thread is at that end wherethe'knurling |0| is andso knows from that in what direction-to turn the assembly in ordertoremove the asscmbly from the cartridge.

From the hereinbefore given descriptionitiwill 'now belapparent that Ihave provided a: knife blade cartridge fuse in which there are,-lneffect, .two main parts, afusible strip. assembly, and a cartridge..When'one is to'replace. the fusible strip in such a fuse, there areonly two main parts to handle sothat there is no real danger of losingan essential part. Afterthe :fuseistrip assembly has been separated fromthe=cantridge,

the nuts, as 49, merelyhave to beloosened and the fuse strip is soformed that its ends may be slipped thereunder, and then the nuts, as;are

"tightened so that there is no danger of :losing such small parts.

The provision of the knurled periphery 65 on largely caughtby theknurled surface 65.

Previous v two-piece cartridges have-been. deficient in this respect asit has been leftfor the user to ascertain, by: trial, which directionaparticular'knifeblade should be turned in order to release the knifeblade as- .sembly from the cartridge.

Venting is also provided for in the two vents as 69 and H at the righthand end of the fuse.

At the left hand end of the fuse, as viewed in the figures, vents 9| and93 provide good release. In addition, however, there is always ventingthrough the associated screw-threads l3 and 89 and for this reason, aspace is provided at I03 so that good escape is provided as soon as thehot gases and metal vapor have traversed the threads I3 and 89.

It should also be noted that when the fuse is properly assembled, thereare spaces showing on each end of the fuse between the metallic cups oneach end and the shoulders of the knife -bla'desythat is, the spaces I05and H11 are clearly evident if the fuse has been properly assembledtightly in position in the cartridge.

- @Although I have particularly described one particular physicalembodiment of invention and explained the construction andprinciple/thereof. nevertheless, I desire to have it understood ;,thatthe form selected is merely illustrative, but does not exhaust thepossible physical embodiments of the idea of means underlying myinvention.

What I'claim as new and desire to secure by Letters Patent is:

l. [3. strip carrier and knife blade assemly, including, in combination,aspacer bar of insulating. material, two metallic knife blades,

one at each end of the spacer bar each knife blade formed oftwo;rectangular;,portions, one

zone side and the spacer .bar on the other /said butt plates eachhavintwo right anglelpor tions,

"one at'each end, one right angle portion directed in one direction andthe otherright ,anglesportionin an opposite direction, onerightangleportiononone buttplate ,abutting the,.end f1 spacer bar andtheotlier right angle portion on ,the; same butt plate abutting; the endof. a tang,

two rivets, one adjacent each end of, the. -spacer bar, eaclrrivetpassing, throughetheaspacer bar and a butt plate and attaching -'the,butt ,=plate firmly to-the spacer bar, saidspacer-ba-r formed with twothrough bores,.one adjacent eachifind,

each tangand each butt-plate. alsoformedwhh ,a through bore aligningwiththe through bores at each endof the spacer bar respectively, twoscrew threaded bolts, one. positioned in ,each of the through bores ofthespacer bar and, passing through atang e1id-and,.a|butt,plate twmnutsand two washers, one of each. on each of the bolts whereby afuse linkprovidedwith athrough bore in each end is attached. spanning,. ,thespace between tang ends, a metallic cupshaped .member positioned on onetang betweenthe adjacent shoulder-and the adjacent spacer bar end, saidmetallic cup formed with a, ,slot therethrough receiving the tang'endgwith an external shoulder adapted for contact with aninternalshoulder of a cartridge end ferrule andywlth a knurled outer peripheryof a diameter adapted to make a close fit in a cartridge'end ferruleinternal bore adjacent inwardly of the, said. in-

- 'ternal shoulder ofa cartridgeiend ferrule.' Said s metallic cupfurther formed with vent, bores therethrough and aqmetallic washerforned with a through'slot positioned on the tan ,btween the metallic cupand the end of the spacer bar covering the said vent bores and means onthe other tang for securing the assembly in a cartridge with themetallic cup pressed tightly against the said internal shoulder of anend ferrule.

2. A fuse strip carrier and knife lade assembly, including, incombination, a spacer bar for insulating material, two metallic knifeblades, one at each end of the spacer bar, each knife blade formed oftwo rectangular portions, one narrower than the other forming tang endand a shoulder, one tang end lapping over one end of the spacer bar andthe other tang end la ng over the other end of the spacer inetallic buttplates, one at each end of the spacer bar interposed between the tangend of a knife blade and the spacer bar, each butt plate formed with aflat plate portion contacting a tang end on one side and the spacer baron the other, said butt plates each having two angle portions, one ateach end, one right angle portion directed in one direction and theother right angle portion in an opposite direction, one right angleportion on one butt plate abutting the end of the spacer bar and theother right angle portion on the same butt plate abutting the end of atang, two rivets, one adjacent each end of the spacer each rivet passingthrough the spacer bar and a butt plate and attaching the butt platefirmly to the spacer bar, means for positioning and securing theassembly in a cartridge, and means for attaching a fusible link betweenthe tang ends.

3. A fuse strip carrier knife blade bly, including, in combination, aspacer bar of insulating material, two metallic knife blades, one ateach end of the spacer bar, each knife blade formed of two rectangularportions, one narrower than the other forming a tang end and a shoulder,one tang end lapping over one end of the spacer bar and the other tangend lapping over the other end of the spacer bar, metallic butt plates,one at each end of the spacer bar interposed between the tan end of thespacer bar interposed between the tan" end knife blade and the spacerbar, each butt plate formed with a flat plate portion contacting a tangend on one side and the spacer bar on the other, said butt plates eachhaving two right angle portions, one at each end, one right angleportion directed in one direction and the other right an le portion inan opposite direction, one right angle por tion on one butt plateabutting the end of the spacer bar and the other right angle portion onthe same butt plate abutting the end of tang, two rivets, one adjacenteach end of the spacer bar, each rivet passing through the spacer barand a butt plate and attaching the butt plate firmly to the spacer bar,spacer bar formed with two through bores, one adjacent each end, eachtang and each butt plate also formed with a through bore aligning withthe through bores at each end of the spacer bar respectively, two screwthreaded bolts, one positioned in each of of the through bores of thespacer bar and pass ing throught a tang end and a butt plate, two nutsand two washers, one of each on each of the bolts whereby a fuse linkprovided with a through bore in each end is attached spanning the spacebetween the tang ends and means for positioning and securing theassembly in a cartridge.

4. A fuse strip carrier and knife blade assembly, including, incombination, a spacer bar of insulating material, two metallic knifeblades, one at each end of the spacer bar, each knife blade formed oftwo rectangular portions one narrower than the other forming a tang enda shoulder, one tang end lapping over one end of the spacer bar and theother tang end lapping over the other end of the spacer bar, metallicbutt plates, one at each end of the spacer bar interposed between thetang end of a knife blade and the spacer bar, each butt plate formedwith a flat plate portion contacting a tang end on one side and thespacer bar on the other, said butt plates each having two right angleportions, one at each end, one right angle portion directed in onedirection, and the other right angle portion in an opposite direction,one right angle portion on one butt plate abutting the end of the spacerbar and the other right angle portion on the same butt plate abuttingthe end of a tang, two rivets, one adjacent each end of the spacer bar,each rivet passing through the spacer bar and a butt plate and attachingthe butt plate firmly to the spacer bar, said spacer bar formed with twothrough bores, one adjacent each end, each tang and each butt plate alsoformed with a through bore aligning with the through bores at each endof the spacer bar respectively, two screw threaded bolts, one positionedin each of the through bores of the spacer bar and passing through atang and a butt plate, two nuts and two washers, one of each on each ofthe bolts whereby a fuse link provided with a through bore in each endis attached spanning the space between tang ends, a metallic cup formedwith a through slot, said slot embracing one of the tang ends betweenthe adjacent butt plate and the adjacent shoulders on the knife blade,said cup formed with a screw thread on a portion of its peripheryadapted to engage an internal screw thread in a cartridge fuse endferrule, said cup further formed with through vent bores, a metallicwasher formed with a through slot, said last mentioned slot surroundingthe last mentioned tang end and interposed between the cup and the lastmentioned butt plate and covering the said vent bores, said cup furtherformed with an end wall extending beyond the external diameter of saidscrew threaded portion a distance suiiioient to lie beyond the outerperiphery of a cartridge end ferrule with which it is associated, theperipheral portion of the said end wall being knurled whereby anon-slipping hand grip is provided, and means associated with the othertang end for co-operation with a cartridge end ferrule positioned on theopposite end of a cartridge from that with which the said metallic cupcooperates.

LEWIS DETCI-I.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,559,890 La Mar Nov. 3, 1925 2,563,566 Von Hoorn Aug. 7, 1951

